The present invention relates to a holographic display element and a method of making the same. More particularly, the present invention relates to a holographic display element for three-dimensionally displaying a three-dimensional model and a plane image, for example, in a superimposed manner. The present invention also relates to a method of making the holographic display element.
There have heretofore been known holographic display elements, e.g. holograms for graphic arts, for three-dimensionally displaying a three-dimensional model and a plane image, for example, in a superimposed manner. Such a holographic display element is made by a method wherein a three-dimensional model and a plane image, for example, are photographically recorded as separate holograms, and reconstructed images of the two holograms are spatially overlaid and recorded as superimposed images in another single hologram.
The conventional holographic display elements suffer, however, from some problems. That is, at an overlap between a pattern forming the foreground and a pattern forming the background, reconstructed light from the background pattern causes additive color mixture with reconstructed light from the foreground pattern, resulting in a change in color and/or a reduction in contrast of the foreground pattern.
In view of the above-described problems with the prior art, an object of the present invention is to provide a holographic display element for three-dimensionally displaying a three-dimensional model and a plane image, for example, in a superimposed manner, which is prevented from causing a change in color or a reduction in contrast of the foreground pattern at an overlap between the foreground pattern and the background pattern, and also provide a method of making the holographic display element.
To attain the above-described object, the present invention provides a holographic display element formed from a single reflection type volume hologram layer, wherein a foreground pattern and a background pattern are recorded so that the two patterns can be reconstructed away from each other in space, and that a portion of the background pattern that is shadowed by the foreground pattern as superimposed thereover is vacant.
In addition, the present invention provides a holographic display element formed from a single reflection type volume hologram layer, wherein a foreground pattern and a background pattern are recorded so that the two patterns can be reconstructed away from each other in space, and that diffracted light for reconstructing the background pattern will not enter a pattern area of the reconstructed foreground pattern.
In addition, the present invention provides a method of making a holographic display element. The method includes the steps of making separately a foreground pattern recording intermediate hologram for forming a foreground pattern image and a background pattern recording intermediate hologram for forming a background pattern image, superimposing the foreground pattern recording intermediate hologram and the background pattern recording intermediate hologram over one another, and directing diffracted light from the foreground pattern recording intermediate hologram and diffracted light from the background pattern recording intermediate hologram to enter the same photosensitive material simultaneously, thereby recording a hologram image. At the step of making a background pattern recording intermediate hologram, the background pattern recording intermediate hologram is made by using a background pattern so formed that a portion thereof that is shadowed by the foreground pattern as superimposed thereover is vacant.
In addition, the present invention provides a method of making a holographic display element. The method includes the steps of making separately a foreground pattern recording intermediate hologram for forming a foreground pattern image and a background pattern recording intermediate hologram for forming a background pattern image, superimposing the foreground pattern recording intermediate hologram and the background pattern recording intermediate hologram over one another, and directing diffracted light from the foreground pattern recording intermediate hologram and diffracted light from the background pattern recording intermediate hologram to enter the same photosensitive material simultaneously, thereby recording a hologram image. The foreground pattern recording intermediate hologram is made as a reflection type volume image hologram in which no diffracted light is produced at least in the reflection direction from any area outside the pattern area of the foreground pattern. The background pattern recording intermediate hologram is made as a reflection type volume hologram in which no information is recorded in a portion corresponding to the pattern area of the foreground pattern and no diffracted light is produced from this portion at least in the reflection direction. The foreground pattern recording intermediate hologram and the background pattern recording intermediate hologram are superimposed over one another and aligned so that the pattern area of the foreground pattern of the foreground pattern recording intermediate hologram fills the non-information recording area of the background pattern recording intermediate hologram, and then recording is carried out.
In the first holographic display element according to the present invention, the foreground pattern and the background pattern are recorded so that a portion of the background pattern that is shadowed by the foreground pattern as superimposed thereover is vacant. Therefore, there is neither a change in color nor a reduction in contrast of the foreground pattern image at the overlap between the foreground pattern image and the background pattern image. Accordingly, the three-dimensional effect is favorably enhanced, and the foreground pattern image and the background pattern image can be viewed three-dimensionally even more effectively. Thus, it is possible to obtain a holographic display element exhibiting abundant creativity in design.
In the second holographic display element according to the present invention, the foreground pattern and the background pattern are recorded so that diffracted light for reconstructing the background pattern will not enter the pattern area of the reconstructed foreground pattern. Therefore, a portion of the background pattern image that corresponds to the shadow of the foreground pattern image is invisible, and there is neither a change in color nor a reduction in contrast of the foreground pattern image at an area where the foreground pattern image lies over the shadowed portion of the background pattern image. Thus, the foreground pattern image and the background pattern image give a natural three-dimensional effect to the observer, and it is possible to obtain a holographic display element exhibiting abundant creativity in design.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.